function newClient() - QRCode

function newClient() {
	ENDPOINT="${SERVER_PUB_IP}:${SERVER_PORT}"

	echo ""
	echo "Tell me a name for the client."
	echo "The name must consist of alphanumeric character. It may also include an underscore or a dash and can't exceed 15 chars."

	until [[ ${CLIENT_NAME} =~ ^[a-zA-Z0-9_-]+$ && ${CLIENT_EXISTS} == '0' && ${#CLIENT_NAME} -lt 16 ]]; do
		read -rp "Client name: " -e CLIENT_NAME
		CLIENT_EXISTS=$(grep -c -E "^### Client ${CLIENT_NAME}\$" "/etc/wireguard/${SERVER_WG_NIC}.conf")

		if [[ ${CLIENT_EXISTS} == '1' ]]; then
			echo ""
			echo "A client with the specified name was already created, please choose another name."
			echo ""
		fi
	done

	for DOT_IP in {2..254}; do
		DOT_EXISTS=$(grep -c "${SERVER_WG_IPV4::-1}${DOT_IP}" "/etc/wireguard/${SERVER_WG_NIC}.conf")
		if [[ ${DOT_EXISTS} == '0' ]]; then
			break
		fi
	done

	if [[ ${DOT_EXISTS} == '1' ]]; then
		echo ""
		echo "The subnet configured supports only 253 clients."
		exit 1
	fi

	BASE_IP=$(echo "$SERVER_WG_IPV4" | awk -F '.' '{ print $1"."$2"."$3 }')
	until [[ ${IPV4_EXISTS} == '0' ]]; do
		read -rp "Client's WireGuard IPv4: ${BASE_IP}." -e -i "${DOT_IP}" DOT_IP
		CLIENT_WG_IPV4="${BASE_IP}.${DOT_IP}"
		IPV4_EXISTS=$(grep -c "$CLIENT_WG_IPV4/24" "/etc/wireguard/${SERVER_WG_NIC}.conf")

		if [[ ${IPV4_EXISTS} == '1' ]]; then
			echo ""
			echo "A client with the specified IPv4 was already created, please choose another IPv4."
			echo ""
		fi
	done

	BASE_IP=$(echo "$SERVER_WG_IPV6" | awk -F '::' '{ print $1 }')
	until [[ ${IPV6_EXISTS} == '0' ]]; do
		read -rp "Client's WireGuard IPv6: ${BASE_IP}::" -e -i "${DOT_IP}" DOT_IP
		CLIENT_WG_IPV6="${BASE_IP}::${DOT_IP}"
		IPV6_EXISTS=$(grep -c "${CLIENT_WG_IPV6}/64" "/etc/wireguard/${SERVER_WG_NIC}.conf")

		if [[ ${IPV6_EXISTS} == '1' ]]; then
			echo ""
			echo "A client with the specified IPv6 was already created, please choose another IPv6."
			echo ""
		fi
	done

	# Generate key pair for the client
	CLIENT_PRIV_KEY=$(wg genkey)
	CLIENT_PUB_KEY=$(echo "${CLIENT_PRIV_KEY}" | wg pubkey)
	CLIENT_PRE_SHARED_KEY=$(wg genpsk)

	# Home directory of the user, where the client configuration will be written
	if [ -e "/home/${CLIENT_NAME}" ]; then
		# if $1 is a user name
		HOME_DIR="/home/${CLIENT_NAME}"
	elif [ "${SUDO_USER}" ]; then
		# if not, use SUDO_USER
		if [ "${SUDO_USER}" == "root" ]; then
			# If running sudo as root
			HOME_DIR="/root"
		else
			HOME_DIR="/home/${SUDO_USER}"
		fi
	else
		# if not SUDO_USER, use /root
		HOME_DIR="/root"
	fi

	# Create client file and add the server as a peer
	echo "[Interface]
PrivateKey = ${CLIENT_PRIV_KEY}
Address = ${CLIENT_WG_IPV4}/32,${CLIENT_WG_IPV6}/128
DNS = ${CLIENT_DNS_1},${CLIENT_DNS_2}

[Peer]
PublicKey = ${SERVER_PUB_KEY}
PresharedKey = ${CLIENT_PRE_SHARED_KEY}
Endpoint = ${ENDPOINT}
AllowedIPs = 0.0.0.0/0,::/0" >>"${HOME_DIR}/${SERVER_WG_NIC}-client-${CLIENT_NAME}.conf"

	# Add the client as a peer to the server
	echo -e "\n### Client ${CLIENT_NAME}
[Peer]
PublicKey = ${CLIENT_PUB_KEY}
PresharedKey = ${CLIENT_PRE_SHARED_KEY}
AllowedIPs = ${CLIENT_WG_IPV4}/32,${CLIENT_WG_IPV6}/128" >>"/etc/wireguard/${SERVER_WG_NIC}.conf"

	systemctl restart "wg-quick@${SERVER_WG_NIC}"

	echo -e "\nHere is your client config file as a QR Code:"

	qrencode -t ansiutf8 -l L <"${HOME_DIR}/${SERVER_WG_NIC}-client-${CLIENT_NAME}.conf"

	echo "It is also available in ${HOME_DIR}/${SERVER_WG_NIC}-client-${CLIENT_NAME}.conf"
}